Increased TIGIT expressing NK cells with dysfunctional phenotype in AML patients correlated with poor prognosis.

AML is the most common blood cancer in adults with a high relapse and an overall poor survival rate. NK cells have been demonstrated to have the capacity to eradicate AML blast, and an impaired NK cell function is involved in AML development and progression. Immune checkpoints are involved in immune escape in various cancers. Immune checkpoints blockade therapy mainly aimed to unleash CD8+T cells function, but NK cells have emerged as new target. However, immune checkpoints profile on NK cells has not been observed in AML patients. Here, we studied the immune checkpoints expression of NK cells from AML patients at initial diagnosis and found increased PD-1, TIGIT and TIM-3 expression compared to NK cells from healthy donors. Further analysis showed that TIGIT expressing NK cells from AML patients had a dysfunctional phenotype, as TIGIT+NK cells exhibit lower antileukemia effect, cytokine production and degranulation compared to TIGIT-NK cells. TIGIT blockade could significantly enhance the function of NK cells. Moreover, AML patients with high frequency of TIGIT+NK cells had higher frequency of poor prognosis risk. Further analysis found that IL-10 upregulated TIGIT expression on NK cells. Thus, TIGIT blockade alone or in combination with other therapy might be potential strategy to treat AML.

Chromatin remodeling by the NuRD complex regulates development of follicular helper and regulatory T cells.

Lineage commitment and differentiation into CD4+ T cell subsets reflect an interplay between chromatin regulators and transcription factors (TF). Follicular T cell development is regulated by the Bcl6 TF, which helps determine the phenotype and follicular localization of both CD4+ follicular helper T cells (TFH) and follicular regulatory T cells (TFR). Here we show that Bcl6-dependent control of follicular T cells is mediated by a complex formed between Bcl6 and the Mi-2ß-nucleosome-remodeling deacetylase complex (Mi-2ß-NuRD). Formation of this complex reflects the contribution of the intracellular isoform of osteopontin (OPN-i), which acts as a scaffold to stabilize binding between Bcl6 and the NuRD complex that together regulate the genetic program of both TFH and TFR cells. Defective assembly of the Bcl6-NuRD complex distorts follicular T cell differentiation, resulting in impaired TFR development and skewing of the TFH lineage toward a TH1-like program that includes expression of Blimp1, Tbet, granzyme B, and IFNγ. These findings define a core Bcl6-directed transcriptional complex that enables CD4+ follicular T cells to regulate the germinal center response.

CD8+T cells expressing both PD-1 and TIGIT but not CD226 are dysfunctional in acute myeloid leukemia (AML) patients.

Acute myeloid leukemia (AML) is one of the most common types of leukemia among adults with an overall poor prognosis and very limited treatment management. Immune checkpoint blockade of PD-1 alone or combined with other immune checkpoint blockade has gained impressive results in murine AML models by improving anti-leukemia CD8+T cell function, which has greatly promoted the strategy to utilize combined immune checkpoint inhibitors to treat AML patients. However, the expression profiles of these immune checkpoint receptors, such as co-inhibitory receptors PD-1 and TIGIT and co-stimulatory receptor CD226, in T cells from AML patients have not been clearly defined. Here we have defined subsets of CD8+ and CD4+ T cells in the peripheral blood (PB) from newly diagnosed AML patients and healthy controls (HCs). We have observed increased frequencies of PD-1- and TIGIT- expressing CD8+ T cells but decreased occurrence of CD226-expressing CD8+T cells in AML patients. Further analysis of these CD8+ T cells revealed a unique CD8+ T cell subset that expressed PD-1 and TIGIT but displayed lower levels of CD226 was associated with failure to achieve remission after induction chemotherapy and FLT3-ITD mutations which predict poor clinical prognosis in AML patients. Importantly, these PD-1+TIGIT+CD226-CD8+T cells are dysfunctional with lower expression of intracellular IFN-γ and TNF-α than their counterparts in HCs. Therefore, our studies revealed that an increased frequency of a unique CD8+ T cell subset, PD-1+TIGIT+CD226-CD8+T cells, is associated with CD8+T cell dysfunction and poor clinical prognosis of AML patients, which may reveal critical diagnostic or prognostic biomarkers and direct more efficient therapeutic strategies.

Intracellular osteopontin regulates homeostasis and function of natural killer cells.

Natural killer (NK) cells play an essential role in the immune response to infection and cancer. After infection or during homeostatic expansion NK cells express a developmental program that includes a contraction phase followed by the formation of long-lived mature memory-like cells. Although this NK cell response pattern is well established, the underlying mechanisms that ensure efficient transition to long-lived NK cells remain largely undefined. Here we report that deficient expression of intracellular osteopontin (OPN-i) by NK cells results in defective responses to IL-15 associated with a substantial increase in the NK cell contraction phase of homeostatic expansion, defective expression of the Eomes transcription factor, and diminished responses to metastatic tumors. The OPN-i-deficient phenotype is accompanied by increased NK cell apoptosis, impaired transition from immature to mature NK cells, and diminished ability to develop memory-like NK cells that respond to mouse cytomegalovirus. Gene pathway analysis of OPN-i-deficient NK cells suggests that the mechanistic target of rapamycin pathway may connect OPN-i to Eomes and T-bet expression by mature NK cells following up-regulation of OPN-i after IL-15 stimulation. Identification of OPN-i as an essential molecular component for maintenance of functional NK cell expansion provides insight into the NK cell response and may provide the basis for improved approaches to immunotherapy for infectious disease and cancer.

Existence of Th22 in children and evaluation of IL-22 + CD4 + T, Th17, and other T cell effector subsets from healthy children compared to adults.

BACKGROUND: Children are prone to get infections, especially in the respiratory system and the gut mainly because their immune system is immature. T cells significantly contribute to the prevention of infections, and different helper T cell (Th) subsets play different anti-pathogen roles. Interleukin (IL)-22 producing by T-helper 22 cells (Th22) play an important role in host defense against Gram-negative bacterial organisms in gut and lung. T-helper 17 cells (Th17) protect against extracelluar bacteria and fungi especially at the epithelial surface. However, there is no report comparing IL-22 producing T cells and Th17 cells in healthy young children to adults. METHODS: Flow cytometry (FCM) was used to observe whether Th22 subset existed in the peripheral blood of healthy young children. Meanwhile, we determined the frequencies of Th subsets including Th17, Th1 and Th2, cytotoxic T (Tc)1 subset, CD4+ and CD8+ memory T cells in the peripheral blood of both young children and adults. RESULTS: In the present study, we demonstrated that Th22 subset existed in peripheral blood of children, with IL-22 mainly secreted by CD4 + CD45RO+ memory T cells. Moreover, we observed that IL-22 + CD4 + T cells and Th subsets including Th17, Th1, and Th2 frequencies of young children (1-6 years old) were significantly lower than adults. While the Th1 frequency from Group A (1-3 years old) was markedly lower than that from Group B (4-6 years old). No significant differences of Th17 or IL-22 + CD4 + T cells frequencies were observed between these two groups. In addition, Tc1 subset frequencies were also remarkably lower in young children than in adults. Furthermore, lower frequencies of CD45RO+ memory CD4+ and CD8+ T cells in young children than in adults, and significant correlation between CD45RO+ memory CD4 + T cells and IL-22 + CD4 + T cells, Th1, Th17 were observed. CONCLUSIONS: Th22 subset exists in the peripheral blood of young children. Compared with adults, there are lower frequencies of IL-22 + CD4 + T cells, as well as Th1, Th17, Th2 and Tc1 subsets in the peripheral blood of young children.

Erratum to: The effect of aging on the frequency, phenotype and cytokine production of human blood CD4 + CXCR5 + T follicular helper cells: comparison of aged and young subjects.

[This corrects the article DOI: 10.1186/1742-4933-11-12.].

The effect of aging on the frequency, phenotype and cytokine production of human blood CD4 + CXCR5 + T follicular helper cells: comparison of aged and young subjects.

BACKGROUND: T cell-dependent B-cell responses decline with age, indicating declined cognate helper activity of aged CD4 + T cells for B cells. However, the mechanisms remain unclear. T follicular helper (Tfh) cells, a novel T helper subset, play an essential role in helping B cells differentiation into long-lived plasma cells in germinal center (GC) or short-lived plasma cells. In the present study, we proposed that there might existe changes of proportion, phenotype or cytokine production of blood Tfh cells in healthy elderly individuals compared with healthy young individuals. RESULTS: The results showed that frequencies of aged blood CXCR5 + CD4 + Tfh cells increased compared with young subjects. Both aged and young blood CXCR5 + CD4 + Tfh cells constitutively expressed CD45RO, CCR7 and CD28, and few of these cells expressed CD69 or HLA-DR, which indicated that they were resting memory cells. There was no significant difference of IL-21 frequency production by aged blood CXCR5 + CD4 + Tfh determined by FACS compared with young individuals, however, aged PBMCs produced significantly higher levels of IL-21 evaluated by ELISA. Furthermore, there were no significant differences of percentages of IFN-γ, IL-4, IL-17 or IL-22 production by aged Tfh cells compared with their counterparts of young individuals respectively. However, frequencies of IL-17+ cells within aged CD4 + CXCR5-T cells were markedly lower than in the young individuals. Furthermore we observed different frequencies of IFN-γ, IL-17, IL-4 or IL-22 production by Tfh or by CD4 + CXCR5- cells in aged and young subjects respectively. CONCLUSIONS: Our data demonstrated that the frequencies of blood memory CXCR5 + CD4 + Tfh cells increased in the elderly population. There were similar frequencies of Th characterized cytokine production such as IL-21, IFN-γ, IL-4, IL-17 or IL-22 in aged and young Tfh cells. However, aged PBMCs produced a significantly higher amount of IL-21 compare to young subjects.

The Association Between Psoriasis and Trace Element Serum Levels and Dietary Intake: Results from USA National Health and Nutrition Examination Survey 2011-2014.

Objective: Psoriasis is a common chronic inflammatory disease. However, trace elements are essential to biochemical processes of the skin, it is suspected that the trace elements are vital in the pathogenesis of psoriasis. Our research is aimed to investigate the association between serum levels and dietary intake levels of selenium, zinc, and copper with psoriasis. Methods: In this cross-sectional study, we utilized the National Health and Nutrition Examination Survey data from 2011 to 2014 to examine the association between psoriasis and serum concentration and dietary intake of trace elements including copper, zinc, and selenium in the US individuals. Our research combined two cycles and weighted the data. Student's t-tests and χ2 test were used. Subgroup analyses and interaction tests were conducted by IBM SPSS Statistics 22 and EmpowerStats. Results: This study indicates that the population with psoriasis has a lower dose of dietary intake selenium than the controls, and risk analysis showed that the men with selenium daily intake >150 mcg/day have a decreasing risk for psoriasis compared to those with daily intaking selenium <75 mcg/day. However, there are no differences on daily intake of selenium, zinc, and copper and serum levels of Zinc and Copper between psoriasis and healthy controls. The current study showed that the psoriasis group was significantly older with a bigger waist circumference, a higher education level, a higher ratio of people with smoke every day, and a higher ratio of people in USA and being non-Hispanic White. Conclusion: This cross-section study showed that a high selenium intake may benefit USA adults from psoriasis, especially for males. The social and cultural background and ethnic differences between the two groups influence the eating and living models, including the trace element intake. The national recommended dietary allowances (RDAs) might be considered to be modified with more reliable investigative clinical data and certain considering the social and cultural models.

Intermittent fasting alleviates IMQ-induced psoriasis-like dermatitis via reduced γδT17 and monocytes in mice.

Psoriasis is a chronic immune mediated inflammatory skin disease with systemic manifestations. It has been reported that caloric restriction could improve severity of psoriasis patients. However, the mechanism of intermittent fasting effects on psoriasis has not been investigated. Caloric restriction is known to reduce the number of circulating inflammatory monocytes in a CCL2-dependent manner. However, it is still unknown whether caloric restriction can improve psoriasis by regulating monocytes through CCL2. In this study, we used imiquimod (IMQ)-induced psoriasis-like mouse model to explore the effects and the mechanisms of intermittent fasting on psoriasis-like dermatitis. We found that intermittent fasting could significantly improve IMQ-induced psoriasis-like dermatitis, and reduce the number of γδT17 cells and IL-17 production in draining lymph nodes and psoriatic lesion via inhibiting proliferation and increasing death of γδT17 cells. Furthermore, intermittent fasting could significantly decrease monocytes in blood, and this was associated with decreased monocytes, macrophages and DC in psoriasis-like skin inflammation. Reduced monocytes in circulation and increased monocytes in BM of fasting IMQ-induced psoriasis-like mice is through reducing the production of CCL2 from BM to inhibit monocyte egress to the periphery. Our above data shads light on the mechanisms of intermittent fasting on psoriasis.

Alteration of T cell subtypes in spleen and antibodies of serum in mice infected with Angiostrongylus cantonensis.

The immune responses of Angiostrongylus cantonensis infection are closely relevant to the host's self-protection and the nematode's pathogenesis. In the present study, BALB/c mice were randomly divided into uninfected control group, infection group 1, and infection group 2. The infection group 1 and infection group 2 were infected with 20 and 40 third-stage larvae of A. cantonensis per mouse, respectively. The splenocytes from the mice were collected and cultured on the 19th and 25th days post-infection; the subtypes of T cells in splenocytes were detected by flow cytometry with fluorescence staining method, and the cytokines in cultured supernatants of splenocytes were assayed by the method of ELISA. The specific IgG and IgE antibodies in sera of the mice were periodically detected by ELISA. The results showed that the percentages of CD4(+) and CD4(+) IL-4(+) T cells in splenocytes of infected mice were much higher (P < 0.05) than those in control mice; however, the percentages of CD4(+) IL-17(+) and CD4(+) IFN-γ(+) T cell were much lower(P < 0.01) after the infection. The levels of CD8(+) T cells in infected mice also rose, but differences between control mice and infected mice were not significant. In comparison with control mice, the concentration of IL-4 in the cultured supernatants of splenocytes in infected mice increased significantly (P < 0.05), but that of IL-17 decreased significantly (P < 0.01). In addition, the number of larvae infected and days after infection may influence levels of the T cell subtypes and the cytokines in spleen, too (P > 0.05). On humoral immunity, the levels of specific IgG antibodies in sera rose a bit at the fifth day post-infection, and reached a peak at the 20th day post-infection; the specific IgE antibodies gradually heightened during first 10 days post-infection; then, it showed a downward trend during the 15th to 25th days post-infection. It is evident that the percentages of CD4(+) T lymphocytes of spleen in the mice infected with A. cantonensis markedly increase and polarize to Th2 phenotypes, and the function of Th17 cells is inhibited. In addition, the elevation of specific IgG antibodies in sera of the infected mice is more significant than that of specific IgE antibodies.

Low-dose IL-2 therapy in autoimmune diseases: An update review.

Regulatory T (Treg) cells are essential for maintaining self-immune tolerance. Reduced numbers or functions of Treg cells have been involved in the pathogenesis of various autoimmune diseases and allograft rejection. Therefore, the approaches that increase the pool or suppressive function of Treg cells in vivo could be a general strategy to treat different autoimmune diseases and allograft rejection. Interleukin-2 (IL-2) is essential for the development, survival, maintenance, and function of Treg cells, constitutively expressing the high-affinity receptor of IL-2 and sensitive response to IL-2 in vivo. And low-dose IL-2 therapy in vivo could restore the imbalance between autoimmune response and self-tolerance toward self-tolerance via promoting Treg cell expansion and inhibiting follicular helper T (Tfh) and IL-17-producing helper T (Th17) cell differentiation. Currently, low-dose IL-2 treatment is receiving extensive attention in autoimmune disease and transplantation treatment. In this review, we summarize the biology of IL-2/IL-2 receptor, the mechanisms of low-dose IL-2 therapy in autoimmune diseases, the application in the progress of different autoimmune diseases, including Systemic Lupus Erythematosus (SLE), Type 1 Diabetes (T1D), Rheumatoid Arthritis (RA), Autoimmune Hepatitis (AIH), Alopecia Areata (AA), Immune Thrombocytopenia (ITP) and Chronic graft-versus-host-disease (GVHD). We also discuss the future directions to optimize low-dose IL-2 treatments.

Low-dose interleukin-2 (IL-2) is a potential treatment for autoimmune diseases. IL-2 is a protein that helps regulate the immune system, and low doses of it can activate regulatory T cells (Tregs), which help control the immune response. This can be beneficial in autoimmune diseases where the immune system attacks healthy tissues. We discuss several clinical trials that have investigated the effectiveness of low-dose IL-2 in treating autoimmune diseases. These trials have shown promising results, with some patients experiencing improvements in symptoms and disease progression. However, more research is needed to determine the safety and effectiveness of low-dose IL-2 as a treatment for autoimmune diseases. IL-2 can also activate other immune cells, which may cause unwanted side effects. Therefore, careful monitoring and dosing are necessary when using this treatment. We should also take note of some of the challenges associated with using low-dose IL-2 as a treatment for autoimmune diseases. For example, it can be difficult to determine the optimal dose and dosing schedule for each patient. In addition, there may be individual differences in how patients respond to low-dose IL-2 treatment. Overall, we believe that low-dose IL-2 shows promise as a treatment for autoimmune diseases, but more research is needed to fully understand its potential benefits and risks.

Epidemiology of Psoriasis and Comorbid Diseases: A Narrative Review.

Psoriasis is a chronic autoimmune inflammatory disease that remains active for a long period, even for life in most patients. The impact of psoriasis on health is not only limited to the skin, but also influences multiple systems of the body, even mental health. With the increasing of literature on the association between psoriasis and extracutaneous systems, a better understanding of psoriasis as an autoimmune disease with systemic inflammation is created. Except for cardiometabolic diseases, gastrointestinal diseases, chronic kidney diseases, malignancy, and infections that have received much attention, the association between psoriasis and more systemic diseases, including the skin system, reproductive system, and oral and ocular systems has also been revealed, and mental health diseases draw more attention not just because of the negative mental and mood influence caused by skin lesions, but a common immune-inflammatory mechanism identified of the two systemic diseases. This review summarizes the epidemiological evidence supporting the association between psoriasis and important and/or newly reported systemic diseases in the past 5 years, and may help to comprehensively recognize the comorbidity burden related to psoriasis, further to improve the management of people with psoriasis.

The suppressive effect of CD25+Treg cells on Th1 differentiation requires cell-cell contact partially via TGF-ß production.

CD25+Treg cells (CD4+CD25+Foxp3+ regulatory T cells) play a central role in the maintenance of peripheral self-tolerance and immune homoeostasis. A previous study showed that CD25+Treg cells suppressed the differentiation and function of Th1 cells in vivo and in vitro. However, the mechanism of suppressing Th1 cell differentiation mediated by CD25+Treg cells remains unclear. In the present study, we found that CD25+Treg cells could reduce the production of IFN (interferon)-γ and the percentage of IFN-γ-, IL-2 and TNF-α-producing cells by CD25-T cells under Th1 cell culture conditions and suppress the differentiation of CD25-T cells into Th1 cells in a dose-dependent manner. Moreover, these CD25+Treg cells could inhibit the activation of CD25-T cells by down-regulating the expression of activation markers CD69 and CD25 and suppress the division and proliferation of CD25-T cells using CFSE (carboxyfluorescein diacetate succinimidyl ester)-labelling and BrdU (5-bromo-20-deoxyuridine) incorporation, respectively. Further studies showed that the suppressive effects of CD25+Treg cells on Th1 cell differentiation required cell-cell contact and was partially restored by the addition of anti-TGF-ß mAb (monoclonal antibody) but not anti-IL-10 mAb, indicating that the suppression mechanism of CD25+Treg cells was cell-cell contact dependent and partially via TGF-ß. This finding strongly indicates a therapeutic role for CD25+Treg cells in Th1-mediated diseases.

Prediction of skin disease using a new cytological taxonomy based on cytology and pathology with deep residual learning method.

With the development of artificial intelligence, technique improvement of the classification of skin disease is addressed. However, few study concerned on the current classification system of International Classification of Diseases, Tenth Revision (ICD)-10 on Diseases of the skin and subcutaneous tissue, which is now globally used for classification of skin disease. This study was aimed to develop a new taxonomy of skin disease based on cytology and pathology, and test its predictive effect on skin disease compared to ICD-10. A new taxonomy (Taxonomy 2) containing 6 levels (Project 2-4) was developed based on skin cytology and pathology, and represents individual diseases arranged in a tree structure with three root nodes representing: (1) Keratinogenic diseases, (2) Melanogenic diseases, and (3) Diseases related to non-keratinocytes and non-melanocytes. The predictive effects of the new taxonomy including accuracy, precision, recall, F1, and Kappa were compared with those of ICD-10 on Diseases of the skin and subcutaneous tissue (Taxonomy 1, Project 1) by Deep Residual Learning method. For each project, 2/3 of the images were included as training group, and the rest 1/3 of the images acted as test group according to the category (class) as the stratification variable. Both train and test groups in the Projects (2 and 3) from Taxonomy 2 had higher F1 and Kappa scores without statistical significance on the prediction of skin disease than the corresponding groups in the Project 1 from Taxonomy 1, however both train and test groups in Project 4 had a statistically significantly higher F1-score than the corresponding groups in Project 1 (P = 0.025 and 0.005, respectively). The results showed that the new taxonomy developed based on cytology and pathology has an overall better performance on predictive effect of skin disease than the ICD-10 on Diseases of the skin and subcutaneous tissue. The level 5 (Project 4) of Taxonomy 2 is better on extension to unknown data of diagnosis system assisted by AI compared to current used classification system from ICD-10, and may have the potential application value in clinic of dermatology.

Control of Germinal Center Localization and Lineage Stability of Follicular Regulatory T Cells by the Blimp1 Transcription Factor.

Follicular regulatory T (TFR) cells are a specialized suppressive subset that controls the germinal center (GC) response and maintains humoral self-tolerance. The mechanisms that maintain TFR lineage identity and suppressive activity remain largely unknown. Here, we show that expression of Blimp1 by FoxP3+ TFR cells is essential for TFR lineage stability, entry into the GC, and expression of regulatory activity. Deletion of Blimp1 in TFR cells reduced FoxP3 and CTLA-4 expression and increased pro-inflammatory cytokines and spontaneous production of autoantibodies, including elevated IgE. Maintenance of TFR stability reflected Blimp1-dependent repression of the IL-23R-STAT3 axis and activation of the CD25-STAT5 pathway, while silenced IL-23R-STAT3 or increased STAT5 activation rescued the Blimp1-deficient TFR phenotype. Blimp1-dependent control of CXCR5/CCR7 expression also regulated TFR homing into the GC. These findings uncover a Blimp1-dependent TFR checkpoint that enforces suppressive activity and acts as a gatekeeper of GC entry.

PIKA as an adjuvant enhances specific humoral and cellular immune responses following the vaccination of mice with HBsAg plus PIKA.

An adjuvant is usually used to enhance the immune response induced by vaccines. The choice of adjuvant or immune enhancer determines the effectiveness of the immune response. Currently, aluminium (Alum, a generic term for salts of aluminium) is the only FDA-approved adjuvant. Alum predominantly induces the differentiation of Th2 cells and thus mediates an antibody immune response. Therefore, there is an urgent need for new adjuvants that enhance not only humoral but also cellular immune responses. In the present study, we demonstrates that PIKA (a stabilized dsRNA) as an adjuvant directly induces the activation and the proliferation of both B and NK cells in vitro. Injection of PIKA into mice results in the production of cytokines in vivo. In addition, the study demonstrates that PIKA promotes the maturation of bone marrow-derived dendritic cells (BMDCs) including up-regulation of the co-stimulatory molecules CD80, CD86 and CD40, and the induction of cytokines such as IL-12p70, IL-12p40 and IL-6. Importantly, after immunization of mice with HBsAg plus PIKA, the presence of PIKA enhances the titers of HBsAg-specific IgG and HBsAg-specific IFN-gamma production. These results demonstrate that PIKA as an adjuvant can promote both humoral and cellular immune responses. These might have an implication in applying PIKA as an adjuvant to be used in the design and development of both therapeutic and preventive vaccines, and used in the clinical study.

Interleukin-22 aggravates murine acute graft-versus-host disease by expanding effector T cell and reducing regulatory T cell.

Graft-versus-host disease (GVHD) as a major complication after allogeneic hematopoietic stem cell transplantation is not well prevented now. We have observed that interleukin-22 (IL-22) produced by Th22, Th1, and Th17 cells participated in GVHD development in our previous study. However, the role of IL-22 in GVHD is still ambiguous. The aim of this study was to illuminate the pathological or protective function and the potential mechanism of IL-22 in the GVHD process. In the present study, we found that compared with mice cotransferred with bone marrow and spleen cells (BS mice) without IL-22 administration, more serious tissue damage and higher GVHD clinical score were observed in BS+IL-22 mice. IL-22 administration was a benefit to early recovery of thymus after irradiation-induced injury. Administration of IL-22 could promote Th1 and Tc1 cell expansion in mesenteric lymph nodes but reduce CD4(+)CD25(+)Foxp3(+) regulatory T (Treg) cell number. Levels of systemic inflammatory cytokines (IFN-γ and TNF-α) were upregulated, while the level of immunosuppressive cytokine IL-10 was downregulated in recipients with IL-22 injection. In conclusion, IL-22, which exacerbates both local immune responses and systemic inflammation of recipients, plays a pathogenic role in the GVHD process. The potential mechanism of IL-22 in GVHD may attribute to increased alloreactive effector Th1 and Tc1 cells and decreased inhibitory Treg cell.